Carton with cover lock



March 21, 1961 R. J. MUTH CARTON WITH COVER Loox Filed April 24, 1958 nited States Patent Oce Patented Mar. 21, 1961 CARTON WITH COVER LOCK Richard J. Muth, Seattle, Wash., assgnor to Container Corporation of America, Chicago, Ill., a corporation of Delaware Filed Apr. 24, 195s, ser. No. 730,685 z claims. 1m29-4s) The present invention relates to folding cartons and more particularly to cartons of tray lform having a cover with a locking tab engageable with a wall of the tray to keep the cover closed.

A princip-al object of the invention is to provide an improved construction of collapsible carton of tray form, combined with a cover carrying a locking tab or tongue designed to enter an opening in a vertical wall of the carton, the construction being such that the tab-receiving Opening tends to ibe distended when the carton is set up.

A further object of the invention is to provide a collapsible tray yform of carton with hinged cover panel having a depending front ap carrying `a locking tab designed to enter a slit in the carton front wall, the connection between the front wall and carton bottom panel being such that movement of the tray section of the carton to set-up condition tends to open the slit to facilitate the insertion therein of the locking tab.

Other `and more specific objects and ladvantages of the present invention will Ibecome apparent as' the description proceeds.

In the drawings illustrating a preferred emlbodirnent of the inventionl Fig. 1 is a perspective view of the carton, showing it set up and with the hinged cover swung down close to its final closing position;

Fig. 2 -is a plan view of the fblank from which the carton is constructed;

Fig. 3 is a fragmentary front elevation, showing the cover in closed position with the locking tab engaged within the slit in the front wall.

Fig. 4 is a fragmentary cross sectional view taken along line 4 4 of Fig. 3 looking downward and in the direction of the arrows; and

Fig. 5 isa fragmentary cross sectional View taken along line 5 5 of Fig. 3, looking in the direction of the arrows.

The carton of the present invention may have a number of specic forms but essentially it comprises a collapsible paperboard tray having a cover with one or more depending flanges, at least one of which is formed with la rigid locking tab or tongue receivable into -a slit in a vertical wall of the tray section. A portion of the hinge line between such vertical wall and the Ibottom panel of the tray section -being curved or `deviated from a straight line, whereby the wall having the slit therein is caused to be deected in the locality of the slit, causing the material along one of the edges of the slit to assume a bowed condition, while the material along the other edge of the slit tends to remain unbowed. By thus causing the slit edges to separate, the cover locking tab may be inserted into the slit with relative ease.

Referring more particularly to the drawings, the carton is preferably formed from a single blank of foldable paperboard ywhich is suitably cut and creased, or scored, to provide a bottom panel 10, `a `front wall panel 11, a rear wall panel 12, and -a cover panel 13, defined from each other by parallel crease lines 14, 15, and 16. At the lateral edges of the blank set o yby fold lines 18, 18 are end walls 19, 19 at the ends of the lbottom panel, corner aps 20, 20 and 21, 21 at the ends of the front wall 11 and rear Wall 12 and cover end anges 22, 22. Attaching ilaps 23, 23 are cam'ed at the forward ends of the end anges 22. A front cover flange 24 projects from the front edge of the cover. This ange land the llaps 23, 23 are lfoldable along fold line 25 extending ylaterally of the fblank.4

Various manners of securing the vertical tray walls together may be employed. In the present instance the walls 19, 19 are diagonally scored to provide fold lines 26, 26 and 27, 27. The main portions of the end walls are then folded in to lie against the bottom panel 10, while the triangular end sections are folded back to lie on the outside of the end walls. Adhesive is applied to these triangular sections. Flaps 20 and 21 are folded to lie against their respective attached wallsy 11 and '12 and 'the walls and flaps are then folded inward to overlie the bottom panel 10 and the infolded end walls. The flaps 20 and 21 will thus be brought into contact with the glued triangular sections of the end walls and will become adhered thereto.

When it is ydesired to set up the tray portion of the carton, it is only necessary to lift up on an opposite pair of the downfolded attached walls. will automatically bring u-p the other opposite walls to vertical position with respect to the bottom 10. Any tendency of the end walls to assume an inwardly inclined position will be taken care of by filling the carton with the desired contents.

The cover anges 22 have diagonal fold lines 29, 29 to form tri-angular end sections yadjacent the aps 23, 23. The desired connection between the front and end panels of the cover may be effected Iby swinging the end section and attached flap 23 of each ange 22 las a unit'so they will corne to rest ilat upon the blank with the triangular section lying against the main portion of flange 22 and the Hap 23 lying ilat upon the cover panel 13. Adhesive is then applied to the exposed surfaces of flaps 23, 23 and the front ange 24 is then folded over to lie flat against the infolded aps 23, 23 and the cover panel 13. After the adhesive has set, the cover anges may be brought simultaneously to vertical position. This may be accomplished by pressing inwardly and upwardly on the end flanges 22, 22, or iby holding panel 13 and swinging the front flange 24 upwardly and outwardly. The particular sequence of applying adhesive to the flaps and folding them to form a collapsed carton is not important.

The front cover flange 24 is secured to the tray front wall 11 by means of a locking tab 30 on the cover flange receivable within a slit 31 cut in the front wall. For the purpose of facilitating entry of the tab into the slit means are provided to cause the material of the front wall at each side of the slit to move relatively in setting up the tray so that one portion at one edge of the slit is moved out of the plane of the other, thereby opening up the slit to present an upwardly directed opening of appreciable width. The locking tab may thus enter the slit in a substantially straight downward movement without requiring any deflection of the tab end. This is particularly desirable in utilizing the carton on high speed, 'automatic machinery.

In the present instance the slit is caused to open when the tray is set up by forming the crease line 14 with a central `portion 32 which deviates from a straight line. This portion of the crease is preferably slightly curved and has its convex' side toward the slit in the front wall. The crease thus is impressed in that portion of the blank which would form a part of the front wall if the crease line had been impressed exactly parallel with the top edge of the wall.

The locking tab 30 preferably has laterally extending This lifting action portions 33, 33 formed `hy cuts 34, 34 at the juncture of the tab with they cover front iange. The overall width of the locking talla measured from the tips of portions 33, 33 is less than the length of the slit.

The central par-t of the slit 31 is preferably formed as Ia straight-line cut extending approximately parallel with the upper and lower wall edges. To furtherfacilitate entry'of the tab within the slitaandto provide-for a more positive locking engagment, the ends ofthey slit terminate in downwardlyA inclined portions'g, 36, Insertion ofthe lockingtab into the-openedl slit and in contact with the slightly bulging front wall tends to cause the lateral tab end portions 33y tobe deflected slightly-awayfrom the normal plane ofthe tab 30. See Fig. 4'. AThis eject, as soon as the tab 30=has entered the slit completely, tends to move the tab ends 33, 33inwar'dly beneath the edge presented by the upper part ofthe slit, thereby llocking these tab ends positivelyvbeneath the wall edge portions forming the upper margin off the slit.

The carton as stated above is preferably formed in a at, collapsed condition with the major portions of the tray end Walls `folded at against the tray bottom, the triangular portions of the end Walls are folded to lie on the outside surfaces of their walls, and such triangular portions are adhered to the adjacent corner flaps 20 and 21. This requires the front and rear walls to be folded inwardly to lie substantially parallel to the bottom panel. The front cover flange is folded tolie against the inside surface of the cover, the major portions kof the cover side flanges are folded outwardly, and the corner aps 23, 23 are adhered to the inside surface of the front flange. As so'formed, the collapsed cartons are delivered to the user. The cartons in the most common practice are opened, filled and closed on high speed automatic carton loading machines which are designed to insert the locking tabs into the front wall slits as a part of their operation. By so forming the cartons that the slit tends to open up in the process of setting up the carton, the successful insertion of the locking tabs into the slits in each carton is substantially assured.

While the foregoing description sets forth a preferred embodiment of the invention, numerous changes may be made in the construction Without departing from the spirit of the invention, and it is therefore desired that the present embodiment be considered as illust-rativeand not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim:

1. A carton formed offoldable paperboard, comprising a tray section having a bottom panel, a front Wall panel integrallyhinged thereto. along a crease line, said front wall P22-@1 having a slit cut therein of whichat least a portion. extends Substantiallyparallel t0 the crease line.

a cover for the tray section including a top panel, front cover ange and a tab depending from an edge of said cover ange `adjacent the/slit in the frontwall panel, the crease line having a portion-thereof located adjacent and substantially coextensive with said slit portion and slightly deviated from a straight line, said front Wall panel having a portion thereof intermediate the slit and the deviated portion ofthe creaseline deiected` out of the general plane of saidfront wall panelto receive and lock. said tab.

2. A carton formed of foldable paperboard, comprising: a trayvhaving aV bottom wall panel and a front wall panel hingedly attached. thereto along a crease line; a coverfor the tray having a top wall panel and a locking tab dependingvtherefrom; said. `front wall panel having therein, for receipt of said tab, a slit. with portion which isrspaced fromrand extends substantially parallel to said crease line; said crease line having a portion substantially coextensive with said slit port-ion and slightly deviated from a straightlinerso that the portion of the front wall panel whichl lies between, said slit andcrease line portionsv is slightlydeilected from the normal plane of said front ywall panel to facilitate insertion of the tab into the slit.

ReferencessCited in the file of this patent UNITED. STATES PATENTS 

